However, it's quite reasonable to prevent business import of goods from abroad. Then, you're basically preventing the producer from assigning different $-value in different regions. Sometimes, that is desirable (market arbitrage), but sometimes, it's not (phisical goods should more closely follow PPP (purchasing power parity), especially if their marginal costs are low).
Why is it reasonable? They aren't counterfeit. They weren't produced in violation of copyright. They aren't dangerous. They aren't stolen. The only reason to ban their import is to protect the copyright holder's business model.
Whether the business model is desirable or not is not the question. The question is whether it deserves explicit protection in law, and I believe it does not.
Well, sometimes there is hardly anything else but copyright that constitutes products (e.g. media, books). Personally, I would also enable the same kind of protection for trademarks (so that iPad could be sold for different price in West and elsewhere).
Regardless of the consequences, it's surprising to me that anybody who doesn't earn money through regional copyright-based price discrimination thinks that it's proper for the government to put the force of law behind such a business model. If the original sale was licensed, what right does the copyright holder have to restrict further transfers of the original copyrighted good, including transfer to another country? I submit that common sense says none.